(i) Field of the Invention
This invention relates to an activity information meter in which a measuring device that measures activity information and an output device that outputs the measured activity information to a user communicates with each other via a body as a medium.
(ii) Description of the Related Art
An activity information meter comprising a measuring device that measures activity information and an output device that outputs the measured activity information to a user in integrated form is large and heavy. Thus, it is conceived to reduce the size and weight of the activity information meter by forming the measuring device and the output device as separate units and thereby dispersing the size and weight. An activity information meter comprising the measuring device and the output device as separate units can be achieved by using an indirect transmission system using static induction or electromagnetic induction which is disclosed in Patent Literature 1, 2 or 3 or a direct transmission system which detects a change in potential at different spots by passing a minute current through a living body which is disclosed in Patent Literature 4 or 5 as a communication technique between the measuring device and the output device.
Patent Literature 1 Japanese Patent Application Laid-Open No. 229357-1998
Patent Literature 2 Japanese Patent Application Laid-Open No. 228524-1998
Patent Literature 3 Japanese Patent Application Laid-Open No. 557-2003
Patent Literature 4 Japanese Patent Application Laid-Open No. 143086-2003
Patent Literature 5 Japanese Patent Application Laid-Open No. 77735-2001
However, when the indirect transmission system disclosed in the above Patent Literatures is used as a communication technique between the measuring device and the output device, there is a problem that a potential is not stabilized and communication is cut off intermittently when a body is moving or the surrounding environment changes because the above system uses the ground as a reference potential. Meanwhile, when the direct transmission system disclosed in the above Patent Literatures is used, there is a problem that a user is subjected to practically inconvenient restrictions one of which is that data transmission is possible only in the transmission direction from the data transmitting device toward the data receiving device because the data receiving device is connected to the earth.
The present invention has been conceived to solve the above problems of the prior art. An object of the present invention is to provide an activity information meter which ensures stable communication between a measuring device and an output device and is highly convenient.